In some cases it seems possible to end up with a "still in progress" error in the global errors which never clears itself until a GoCD restart, unless you delete the pipeline (possibly if you re-run it again?) or something like that.

Probably a race condition between two users; however it's not clear if it's supposed to auto-resolve somehow.

Might come from the StageActiveChecker? There are also some other errors that sometimes happen.